Collide with angle object

Question

I'm developing a mirror for lazer beam(Ball sprite). There I'm trying to redirect the laze beam according to the ration degree of the mirror(Rectangle). How can I collide the ball to the correct angle if the colliding object is with some angle(45 deg) rather than colliding back.

here is an screen shot of my work

here is my code:

protected override void Initialize()
{
    // TODO: Add your initialization logic here
    ballPosition = new Vector2(this.GraphicsDevice.Viewport.Width / 2,
                   this.GraphicsDevice.Viewport.Height * 0.25f);
    blockPosition = new Vector2(this.GraphicsDevice.Viewport.Width / 2,
                               this.GraphicsDevice.Viewport.Height /2);
    ballVelocity = new Vector2(0, 1);

    base.Initialize();
}

protected override void LoadContent()
{
    // Create a new SpriteBatch, which can be used to draw textures.
    spriteBatch = new SpriteBatch(GraphicsDevice);

    ballTexture = Content.Load<Texture2D>("ball");
    blockTexture = Content.Load<Texture2D>("mirror");

    //create rectangles based off the size of the textures
    ballBounds = new Rectangle((int)(ballPosition.X - ballTexture.Width / 2),
    (int)(ballPosition.Y - ballTexture.Height / 2), ballTexture.Width, ballTexture.Height);

    blockBounds = new Rectangle((int)(blockPosition.X - blockTexture.Width / 2),
    (int)(blockPosition.Y - blockTexture.Height / 2), blockTexture.Width, blockTexture.Height);

    origin.X = blockTexture.Width / 2;
    origin.Y = blockTexture.Height / 2;
    // TODO: use this.Content to load your game content here
    Font1 = Content.Load<SpriteFont>("SpriteFont1");
    FontPos = new Vector2(graphics.GraphicsDevice.Viewport.Width - 100, 20);

}

private float RotationAngle;
  float circle = MathHelper.Pi * 2;
  float angle;

protected override void Update(GameTime gameTime)
{
    //check for collision between the ball and the block, or if the ball is outside the bounds of the screen

    if (ballBounds.Intersects(blockBounds) || !GraphicsDevice.Viewport.Bounds.Contains(ballBounds))
    {
        //we have a simple collision!
        //if it has hit, swap the direction of the ball, and update it's position
        ballVelocity = -ballVelocity;
        ballPosition += ballVelocity * ballSpeed;
    }
    else
    {
        //move the ball a bit
        ballPosition += ballVelocity * ballSpeed;
    }

    //update bounding boxes
    ballBounds.X = (int)ballPosition.X;
    ballBounds.Y = (int)ballPosition.Y;

    blockBounds.X = (int)blockPosition.X;
    blockBounds.Y = (int)blockPosition.Y;

    keyboardState = Keyboard.GetState();

    float val = 1.568017f/90;

    if (keyboardState.IsKeyDown(Keys.Space))
        RotationAngle = RotationAngle + (float)Math.PI;

    if (keyboardState.IsKeyDown(Keys.Left))
        RotationAngle = RotationAngle - val;

    angle = (float)Math.PI / 4.0f;  // 90 degrees
    RotationAngle = angle;
    //   RotationAngle = RotationAngle % circle;
        displayText = RotationAngle.ToString();
    base.Update(gameTime);
}

protected override void Draw(GameTime gameTime)
{
    GraphicsDevice.Clear(Color.CornflowerBlue);

    spriteBatch.Begin();

    // Find the center of the string
    Vector2 FontOrigin = Font1.MeasureString(displayText) / 2;
    spriteBatch.DrawString(Font1, displayText, FontPos, Color.White, 0, FontOrigin, 1.0f, SpriteEffects.None, 0.5f);
    spriteBatch.Draw(ballTexture, ballPosition, Color.White);
    spriteBatch.Draw(blockTexture, blockPosition,null, Color.White, RotationAngle,origin, 1.0f, SpriteEffects.None, 0f);

    spriteBatch.End();
    base.Draw(gameTime);
}

Answer 1

You should know that, if an object collides on a surface, the object velocity vector will be reflected on the normal vector of the surface.

You need to compute the normal vector at the point of contact. The component of the velocity along the normal will switch direction while the component of velocity perpendicular to the normal will remain the same.

This link should be useful.